Engine cylinder intake ports, or cylinder head intake ports and the like, may be configured to induce rotation or swirl of the fuel/air intake charge as it is supplied to the combustion chamber. Generally, intake port or passage designs which are intended to induce such charge swirl lack effectiveness across the full operating or lift range of the engine intake valves. While some designs are effective to induce swirl at low valve lifts, they lose substantial effectiveness at high valve lift. Similarly, intake port designs intended to induce charge swirl at high valve lifts have had little effect on the charge flow direction at low valve lift. In general, intake port or passage configurations which have been effective in creating significant charge swirl during both low and high valve lift operation have also, due to increased resistance to flow, resulted in a reduction of the fuel/air charge mass entering each cylinder during the intake stroke, reducing the volumetric efficiency of the engine.
In view of significant interest in utilizing increased charge swirl in spark ignited internal combustion engines, such as gasoline engines used in automotive applications, a need remains for a simple, fixed geometry intake port configuration which is capable of providing substantial fuel/air charge swirl together with high volumetric charging efficiencies across the valve lift profile.